In securing off-shore structures in place, it is a common practice to drive piles into the sea bed and to secure the off-shore structure to these embedded piles. Generally, such piles consist of a follower pile coupled to a skirt pile with the elevated free end of the former being hammered upon to drive the latter into place.
One procedure for driving piles into the sea bed is to weld together enough pile sections until the lower end of the pile rests on the sea floor and the upper end of the pile extends above the water surface. This upper end is then hammered upon to drive the lower end into the sea bed, however, after driving the pile, it is undesirable to leave its entire length extending above the sea floor because of the resulting stresses that will be created. Therefore, divers are normally sent down to separate and remove this extra length which is a very expensive operation.
Another procedure for pile driving involves the use of a Vetco drivable pile connector. The Vetco tool is used to temporarily connect a follower pile to a skirt pile and then lower this combination to the sea floor. A hammer is subsequently applied to the upraised follower pile for driving the skirt pile in place, however, the Vetco tool is difficult to release and retrieve once the driving is completed and on occasion it has been known to fail. Additionally, although the Vetco tool is costly, it is often more expensive to retrieve it from deep water than it is worth thus this costly tool is often abandoned on the sea floor.
Additional devices for removably coupling piles together require electricity or hydraulic pressure for operation and these requirements merely compound the already complicated process of driving piles into the sea bed.
It is thus an object of this invention to provide a lowering and coupling assembly which enables a follower pile to be easily separable from a skirt pile thereby enabling it to be retrieved after being lowered coupled to a skirt pile.
It is another object of this invention to provide a lowering and coupling assembly that does not require electricity or hydraulic pressure for operation. It is a further object of this invention to provide a pile coupler that is simple to use, rugged in design and sturdy enough to withstand constant pounding as the coupled skirt pile is driven into the sea floor. It is another object of this invention to enable the lowering and coupling assembly to be easily secured to a skirt pile resting on the sea floor.